The invention relates to a method for displacing an image transferred using electromagnetic radiation and to an apparatus for performing the method.
A known method and an apparatus for using electromagnetic radiation to transfer images or reproductions corresponding to a mask onto a photo-sensitive layer of a substrate is disclosed in U.S. Pat. No. 5,625,436. In accordance with the disclosure, are bodies that are arranged rotatable about axes and the refraction index of which is different from the refraction index of the ambient air are present in the beam path between the mask and the substrate, and which are embodied as planar glass plates. These bodies can be adjusted by means of suitable drives corresponding to the provided image displacement.
As is known, an electromagnetic beam that strikes, at an angle, the beam refracting body or a medium having a different density that is embedded in a surrounding medium and that has a planar surface is, in particular, refracted when it enters the medium. If the opposing interface of the body or medium is parallel to the incident surface, when the beam exits the medium, it is refracted again at the same angle in the opposing direction because of symmetry. Thus, the beam is offset, and the magnitude of the offset is a function of the angle between the beam and the body or medium, the latter which is embodied, in particular, as a plane parallel glass plate. This property is used for adjustably laterally displacing the reproduction generated by means of an electromagnetic beam, wherein the medium, in particular the plane parallel plate, is arranged rotatable in the aforesaid beam. The accuracy with which the reproduction position can be adjusted in this manner is a function of how precise and reproducible is the angle of adjustment of the bodyor medium, for example, the plate.
Furthermore an apparatus for optically measuring the inclination of a surface of a wafer is known from U.S. Pat. No. 5,218,415, in which a light beam is reflected on the surface of the wafer. The beams reflected in different directions corresponding to the inclination of the wafer are aligned parallel to one another by a lens and supplied to a unit for determining the angle of inclination.
Moreover, sensors that are embodied as interferometers and that contain a radiation-refracting body are known from laid-open specification DE 38 20 170 A1 and patent specification DD 239 658 A1. The beam refracting body is arranged in the beam path of a reference radiation such that the angle of incidence of the radiation onto the surface of the radiation-refracting body can be changed based on its movements. Signals that correspond to the movements of the aforesaid body are generated by overlaying the radiation that penetrates the aforesaid body and the reference radiation due to the resultant interference.
Proceeding from this point, the object of the invention is to refine the method and the apparatus of the aforesaid type with low complexity such that an optimized and/or precise image displacement is attained. Moreover, a high resolution adjustment of the image position and/or a high resolution control of the rotation of the radiation-refracting body provided for the image displacement is also to be provided. The method should be simple to perform, it should be possible to perform the method with reproducible values, and the apparatus should not be structurally complex.